1661445406 has 4 divisors (see below), whose sum is σ = 2492168112. Its totient is φ = 830722702.

The previous prime is 1661445371. The next prime is 1661445407. The reversal of 1661445406 is 6045441661.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661445407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 415361350 + ... + 415361353.

It is an arithmetic number, because the mean of its divisors is an integer number (623042028).

Almost surely, 2^1661445406 is an apocalyptic number.

1661445406 is a deficient number, since it is larger than the sum of its proper divisors (830722706).

1661445406 is an equidigital number, since it uses as much as digits as its factorization.

1661445406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 830722705.

The product of its (nonzero) digits is 69120, while the sum is 37.

The square root of 1661445406 is about 40760.8317628578. The cubic root of 1661445406 is about 1184.3917085485.

The spelling of 1661445406 in words is "one billion, six hundred sixty-one million, four hundred forty-five thousand, four hundred six".